Heel fixing structure for women&#39;s shoe

ABSTRACT

A heel is readily and firmly fastened to the insole of a woman&#39;s heeled shoe. A fastening bolt ( 15 ) with a head ( 15   a ) is screwed through a washer ( 16 ) and an insole ( 12 ) into a reinforcing shaft ( 14 ) embedded in a heel ( 13 ). The reinforcing shaft ( 14 ) includes a thin lower portion ( 14   a ) having a small external diameter fixed to a thick upper portion ( 14   b ) having a large external diameter. The thick fastening bolt ( 15 ) is screwed into the thick portion ( 14   b ) such that the heel ( 13 ) is firmly fastened to the insole ( 12 ) with the reinforcing shaft ( 14 ).

TECHNICAL FIELD

The present invention relates to a heel fixing structure for fastening a heel to a woman's shoe such as a high-heeled shoe.

BACKGROUND ART

According to a conventional woman's high-heeled shoe as illustrated in FIG. 10, a separate synthetic-resin heel 3 is fastened to an insole 2 of a shoe body 1 with nails 4. A metal pipe 5 is embedded in the heel 3 to prevent breakage of the slender heel 3 during the use. The metal pipe 5 includes a heel-tip accessory 6 made of a material such as rubber at the bottom-end thereof.

A large nail 4 a such as a helical nail is driven along the central axis of the heel 3 from the top surface of the insole 2 for rigidly fastening the heel 3 to the insole 2. In addition, short thin nails 4 b are driven around the large nail 4 a to reinforce the large nail 4 a and prevent rotation of the heel 3.

The insole 2 generally consists of multiple layers and a narrow metal shank lying between two central layers for the reinforcement and resiliency of the insole 2. The large nail 4 a and the thin nails 4 b thus must be driven substantially along the central axis of the heel 3 so as to avoid the contact with the shank in the insole 2 and the metal pipe 5 inside the heel 3. This requires highly accurate positioning of the nails.

Even slight misalignment in the position or angle of these nails results in a defective shoe having the large nail 4 a and the thin nails 4 b appearing from the heel 3, as illustrated in FIG. 11. This leads to low manufacturing efficiency and high production costs.

To solve such a problem, Patent Literatures 1 and 2 disclose techniques of fastening a heel to an insole without nails. These techniques enable fastening of a heel without driving nails and therefore can reduce the number of defective shoes.

That is to say, according to the techniques in Patent Literatures 1 and 2, a self-tapping screw 7 is forcedly screwed into a metal pipe 8 inside the heel 3 while tapping the inner surface of the metal pipe 8 to fasten the heel 3 to the insole 2, as illustrated in FIG. 12.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Unexamined Patent Application     Publication No. 2010-48325 -   Patent Literature 2: Registered Japanese Utility Model No. 3112359

SUMMARY OF INVENTION Technical Problem

The techniques in Patent Literatures 1 and 2 ensure fastening of the heel 3 to the insole 2 with the self-tapping screw 7. In general, a pin heel 3 having an edge with a diameter of 10 mm or smaller, for example, can accept only a thin metal pipe 8. Unfortunately, a thin self-tapping screw 7 fittable within such a thin metal pipe 8 cannot provide sufficient fastening strength.

Moreover, screwing of the self-tapping screw 7 into the metal pipe 8, which involves tapping or threading of the metal pipe 8, cannot be readily achieved by manual operation and requires mechanical devices for tapping and threading. Additionally, during the tapping, the metal pipe 8 may cause relative rotation or detachment to/from the heel 3.

An object of the present invention, which has been accomplished to solve the above problems, is to provide a heel fixing structure for a woman's shoe that enables easy and rigid fastening of a heel to an insole.

Solution to Problem

To achieve the above object, a heel fixing structure to an insole for a woman's shoe according to the present invention includes:

a heel;

a metal reinforcing shaft including a thin lower portion and a thick upper portion having a larger external diameter than the external diameter of the thin portion, the thick portion including a first thread groove on the inner surface, the reinforcing shaft being embedded in the heel in the longitudinal direction of the heel; and

a fastening bolt screwed through the insole into the first thread groove to fasten the heel to the insole.

Advantageous Effects of Invention

The heel fixing structure for a woman's shoe according to the present invention can achieve simple, rigid, and secure fastening by screwing of a thick fastening bolt. This structure can therefore significantly reduce the number of defective shoes due to failure of nailing, and is applicable to a pin-heel shoe.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a heel in the completed state according to Embodiment 1;

FIG. 2 is a perspective view of a reinforcing shaft;

FIG. 3 is a cross-sectional view of a heel embedded with a reinforcing shaft;

FIG. 4 is a perspective view of a reinforcing shaft according to a modified embodiment;

FIG. 5 is a side view of a fastening bolt according to a modified embodiment;

FIG. 6 is a cross-sectional view of a heel fastened with a fastening bolt according to a modified embodiment;

FIG. 7 is a cross-sectional view of a heel according to Embodiment 2;

FIG. 8 is a cross-sectional view of a heel according to Embodiment 3;

FIG. 9 is a cross-sectional view of a heel according to modified Embodiment 3;

FIG. 10 is a cross-sectional view of a heel having a conventional heel fixing structure;

FIG. 11 is a cross-sectional view of a defective heel having a conventional heel fixing structure; and

FIG. 12 is a cross-sectional view of a heel having another conventional heel fixing structure.

DESCRIPTION OF EMBODIMENTS

The present invention will now be described in detail based on embodiments illustrated in FIGS. 1 to 9.

Embodiment 1

FIG. 1 is a cross-sectional view of a heel of a completed woman's high-heeled shoe according to Embodiment 1. A synthetic-resin heel 13 is in contact with the bottom of an insole 12 made of a material such as leather in a shoe body 11. A reinforcing shaft 14 is embedded in the heel 13 by injection molding, and a fastening bolt 15 having a head 15 a is screwed via a washer 16 into the reinforcing shaft 14 such that the heel 13 is firmly fastened to the insole 12. The insole 12 is firm enough to hold the heel 13 and includes multiple layers composed of various materials. A narrow metal shank 12 c is sandwiched between a lower layer 12 a and an upper layer 12 b. The shank 12 c serves to reinforce the insole 12, keep the shape and provide resiliency of the insole 12. A sock liner 17 and a bottom sole 18 are respectively attached to the upper and lower surfaces of the insole 12.

FIG. 2 is a perspective view of the reinforcing shaft 14. The metal reinforcing shaft 14 includes a cylindrical thin lower portion 14 a and a thick upper portion 14 b having the external diameter larger than that of the thin portion 14 a such that the top-end of the thin portion 14 a fits within the thick portion 14 b. For example, the thin portion 14 a has a 5-mm external diameter, 3-mm internal diameter, and 50-mm length; while the thick portion 14 b has a 10-mm external diameter, 5-mm internal diameter, and 25-mm length. The thin portion 14 a is integratedly welded to the thick portion 14 b. The thick portion 14 b includes a thread groove 14 c on the inner surface to receive the fastening bolt 15, and optional protrusions 14 d on the outer surface.

During injection molding of the heel 13, the reinforcing shaft 14 is embedded in the heel 13 such that the thin portion 14 a which extends along the heel 13 in the longitudinal direction of the heel 13 does not appear from the bottom of the heel 13 and such that the thick portion 14 b does not protrude from the top of the heel 13.

As illustrated in FIG. 3, the insole 12 includes an opening 12 d to receive the fastening bolt 15 and a taper 12 e is provided around the opening 12 d. The shank 12 c in the insole 12 has an opening or a slit in communication with the opening 12 d to receive the fastening bolt 15.

The heel 13 is temporarily fixed to the insole 12 by means such as adhesion before screwing of the fastening bolt 15 into the reinforcing shaft 14. The fastening bolt 15 is screwed through the washer 16 and the opening 12 d of the insole 12 into the thread groove 14 c with a cross-slot screwdriver applied to the cross slot on the head 15 a of the fastening bolt 15 such that the heel 13 is fixed to the insole 12 with the head 15 a and the washer 16. In particular, the washer 16 engaging with a part of the shank 12 c via the upper layer 12 b further reinforces the fastening.

Furthermore, one or several optional thin nails 19 may be driven around the fastening bolt 15 so as to avoid the shank 12 c. This prevents accidental relative rotation of the heel 13 to the insole 12 during the use. The protrusions 14 d prevent relative rotation and detachment of the reinforcing shaft 14 to/from the heel 13 during screwing of the fastening bolt 15 into the thick portion 14 b. Additionally, the bottom-end of the thin portion 14 a is provided with a heel-tip accessory 20 made of a material such as rubber and having a convex 20 a fittable within the thin portion 14 a.

Thus, in Embodiment 1, the fastening bolt 15, which completely functions a substitute for a conventional large nail 4 a and a small number of thin nails 19, can significantly reduce the number of defective shoes caused by failure of nailing.

According to Embodiment 1, the reinforcing shaft 14 includes the thin portion 14 a with a small external diameter and the thick portion 14 b with a large external diameter thereabove. This enables, even in a pin-heel shoe, embedding of the reinforcing shaft 14 in the heel 13, and screwing of the thick fastening bolt 15 into the thick portion 14 b, thereby achieving rigid fastening. In particular, the thickness difference in the reinforcing shaft 14 between the thin portion 14 a and the thick portion 14 b prevents downward shift of the reinforcing shaft 14 in the heel 13 caused by a load from the above during screwing of the fastening bolt 15 or during the use of the shoe.

Although the reinforcing shaft 14 according to Embodiment 1 includes the thin portion 14 a and the thick portion 14 b that are welded together, the thin portion 14 a having an upper-external thread ridge may be screwed into the thread groove 14 c of the thick portion 14 b. Alternatively, the thin portion 14 a may be connected to the thick portion 14 b by swaging or adhesion, for example.

Also, the reinforcing shaft 14 may have tapered thick portion 14 b connected to the thin portion 14 a as illustrated in FIG. 4( a), or may be an integrated member having an entirely tapered shape as illustrated in FIG. 4( b).

The cross sections of the thin portion 14 a and the thick portion 14 b are not limited to a circle, and may be a polygon or an ellipse, for example. In particular, the thick portion 14 b having a polygonal shape prevents relative rotation to the heel 13 during screwing of the fastening bolt 15. Additionally, the thin portion 14 a is not limited to a pipe and may be a solid shaft with a hole provided at the bottom-end for receiving the heel-tip accessory 20.

Any countermeasure is required to prevent scratch on the user's sole by the head 15 a of the screwed fastening bolt 15 which is not parallel with the top surface of the insole 12. One solution to the problem is to provide a fastening bolt 15′ with an inclined head 15 a illustrated in FIG. 5, the fastening bolt 15′ being fastened such that the top surface of the head 15 a is parallel with the top surface of the insole 12 as illustrated in FIG. 6.

Embodiment 2

According to the above-described Embodiment 1, the reinforcing shaft 14 is embedded in the heel 13 by the injection molding of the heel 13.

In contrast, according to Embodiment 2, a reinforcing shaft 22 including a thin portion 22 a connected to a thick portion 22 b is driven into a hole 21 a of a heel 21, as illustrated in FIG. 7. The hole 21 a has substantially the same shape as that of the reinforcing shaft 22.

The thick portion 22 b may have anti-rotational means such as blades disposed on its outer surface in the longitudinal direction to prevent the rotation of the reinforcing shaft 22 during the screwing of the fastening bolt 15. Also, the reinforcing shaft 22 may have a shape as illustrated in FIG. 4.

As described above, the heel 21 including the reinforcing shaft 22 driven into the heel 21 is attached to the insole 12, and then the fastening bolt 15 or 15′ is screwed into a thread groove 22 c of the thick portion 22 b in the same manner as Embodiment 1. This enables rigid fastening of the heel 21 to the insole 12.

Embodiment 2 is especially effective for the heel 21 made of wood.

Embodiment 3

FIG. 8 is a cross-sectional view for Embodiment 3. According to Embodiment 1, the fastening bolt 15′ in modified Embodiment 1 is used, so that the head 15 a is parallel with the top surface of the insole 12.

In contrast, a metal reinforcing shaft 31 according to Embodiment 3 formed through a technique such as casting to be embedded in the synthetic-resin heel 13 has the fastening bolt 15 and a thin portion 31 a which are attached to the reinforcing shaft 31 in different directions in a thick portion 31 b. In more specific, the thick portion 31 b, which is connected to the thin portion 31 a to form the reinforcing shaft 31, includes a thread groove 31 c for receiving the fastening bolt 15 such that the top surface of the head 15 a is parallel with the top surface of the insole 12, and a thread groove 31 d for receiving the thin portion 31 a such that the thin portion 31 a extends along the heel 13 in the longitudinal direction of the heel 13. The thin portion 31 a may be connected to the thick portion 31 b by a technique such as welding or adhesion.

Since the top surface of the head 15 a of the fastening bolt 15 screwed into the thick portion 31 b is parallel with the top surface of the insole 12, scratching on the user's sole by the head 15 a can be prevented.

FIG. 9 illustrates modified Embodiment 3, in which the thick portion 31 b of the reinforcing shaft 31 includes a thread groove 31 e having a small diameter beside and parallel to the thread groove 31 c for receiving the fastening bolt 15. In addition to the fastening bolt 15 screwed into the thread groove 31 c, a small auxiliary bolt 32 is screwed into the thread groove 31 e to fasten the heel 13 to the insole 12.

Such a structure having the two bolts 15 and 32 screwed into the reinforcing shaft 14 further reinforces the fastening of the insole 12.

INDUSTRIAL APPLICABILITY

The present invention is applicable to not only high-heeled shoes but also middle-heeled shoes and low-heeled shoes.

REFERENCE SIGNS LIST

-   11 shoe body -   12 insole -   12 c shank -   12 d opening -   13, 21 heel -   14, 22, 31 reinforcing shaft -   14 a, 22 a, 31 a thin portion -   14 b, 22 b, 31 b thick portion -   14 c, 22 c, 31 c, 31 d, 31 e thread groove -   14 d protrusion -   15, 15′ fastening bolt -   15 a head -   16 washer -   17 sock liner -   18 bottom sole -   19 thin nail -   20 heel-tip accessory -   32 auxiliary bolt 

What is claimed is: 1-9. (canceled)
 10. A heel fixing structure to an insole for a woman's shoe, comprising: a heel; a metal reinforcing shaft comprising a thin lower portion and a thick upper portion having a larger external diameter than the external diameter of the thin portion, the thick portion comprising a first thread groove on the inner surface, the reinforcing shaft being embedded in the heel in the longitudinal direction of the heel; and a fastening bolt screwed through the insole into the first thread groove to fasten the heel to the insole.
 11. The heel fixing structure for a woman's shoe according to claim 10, wherein the heel is fixed to the insole with a head of the fastening bolt and a washer provided between the head and the insole by screwing the fastening bolt.
 12. The heel fixing structure for a woman's shoe according to claim 11, wherein the heel comprising synthetic resin, and the reinforcing shaft is embedded in the heel by injection molding.
 13. The heel fixing structure for a woman's shoe according to claim 12, wherein the thin portion and the fastening bolt are screwed in different directions in the thick portion such that the top surface of the head of the fastening bolt is parallel with the top surface of the insole.
 14. The heel fixing structure for a woman's shoe according to claim 13, further comprising an auxiliary bolt, wherein the thick portion further comprises a second thread groove beside the first thread groove, the second thread groove having a smaller diameter than that of the first thread groove, and the fastening bolt is screwed into the first thread groove, and the auxiliary bolt is screwed into the second thread groove.
 15. The heel fixing structure for a woman's shoe according to claim 14, wherein the internal diameter of the thick portion is the same as the external diameter of the thin portion.
 16. The heel fixing structure for a woman's shoe according to claim 15, wherein the thick portion further comprises protrusions on the outer surface of the thick portion, the protrusions being for preventing relative rotation and/or detachment of the reinforcing shaft to/from the heel.
 17. The heel fixing structure for a woman's shoe according to claim 15, wherein the thin portion is connected to the thick portion by any of welding, screwing, swaging, and adhesion.
 18. The heel fixing structure for a woman's shoe according to claim 11, wherein the reinforcing shaft is embedded in a hole provided in the heel. 